1. Field of the Invention
The present invention relates to wireless communications, and more particularly to a multi-band low noise amplifier (LNA) and a radio frequency (RF) receiver including the multi-band LNA.
2. Description of the Related Art
Mobile communication equipment, such as cellular phones, personal digital assistants, mobile personal computer terminals, etc., have become widely used as advancements have been made in mobile communication systems. Mobile communication systems may be capable of transmitting/receiving signals in various frequency bands, such as 800 MHz to 1.0 GHz, 1.5 GHz to 2.0 GHz, etc.
Components of mobile communication equipment must be miniaturized and have enhanced performance characteristics. Demand for reducing the size and manufacturing costs of mobile communication equipment is ever increasing. Additionally, studies for reducing the size and manufacturing costs of the components have been actively conducted.
A conventional integrated inductor is an important passive device used for impedance matching in an integrated circuit. The conventional integrated inductor typically occupies the largest circuit area in an integrated circuit. Because impedance varies depending on frequency, and the size of an inductor increases as frequency decreases. The manufacturing cost also increases as the size of the integrated circuit increases. Accordingly, various efforts have been made to develop integrated inductors that are relatively small in size, but that maintain high impedance characteristics and high quality factors.
An RF transceiver supports multi-bands and multi-modes, and recent RF transceivers require a form factor having a smaller size due to miniaturization of mobile communication equipment, such as cellular phones. However, supporting multi-bands and multi-modes in smaller mobile communication equipment is very difficult. Additionally, insufficient circuit area may be a concern in integrated circuit design, particularly when inductors are integrated, for example, in a low noise amplifier (LNA).
A conventional LNA includes a common-source structure or a cascode structure. In N multi-band transceivers, N LNAs in parallel are included (N being a natural number over 2). In particular, LNAs require characteristics of low noise and sufficient gain, thus requiring narrow band designs. Accordingly, more inductors are included in the transceivers as more frequency bands are required, and inductor circuit areas should be reduced.